Device for the treatment of a web substrate in a plasma enhanced process

ABSTRACT

A device for treating a web substrate in a plasma enhanced process. The device includes a treatment station with a vacuum process chamber. A plasma treatment unit is allocated to the treatment station which is designed to form a plasma zone within the process chamber for treating a surface of the web substrate. The device further includes a transporting system for continuously transporting the web substrate through the treatment station with an unwind roller and a rewind roller, wherein the transporting system defines a transporting path of the web substrate through the process chamber. The plasma treatment unit includes an extensive antenna and a radiofrequency generator for exciting the extensive antenna to a resonant frequencies.

The invention lies in the field of plasma enhanced treatment ofsubstrate surfaces. The invention relates to a device and method forcontinuously treating a web substrate in a plasma enhanced process. Thedevice contains at least one treatment station with a process chamber,wherein at least one plasma treatment unit is allocated to the treatmentstation which is designed to form a plasma zone within the processchamber for treating a surface of the web substrate. The device furthercontains a transporting system for continuously transporting the websubstrate through the treatment station, with an unwind roller and arewind roller, wherein the transporting system defines a transportingpath of the web substrate through the process chamber.

Web substrates, as e.g. polymer films, are e.g. coated with one or morelayers in order to modify specific properties of the web substrate. Websubstrates are for example coated with gas, vapour and/or aroma tightbarrier layers in order to prohibit the passage of gas, vapour and aromathrough the web substrate. Such barrier layers may consist of Siliconoxide or Aluminium oxide.

Gas and aroma tight web substrate are especially suitable for packagingmaterial. Such packaging material finds e.g. application in the field offood and pharmaceutical packaging and is in particular intended toreplace aluminium in packaging material.

In other applications coating layers are intended to modify the opticalproperties of the web substrate.

Generally, the coatings produced in a plasma enhanced process arerelatively thin and lie e.g. in the nano-meter range. For this reasonthe flexible properties of the web substrate remain preserved. Further,the structure of the coating is not adversely affected by the flexiblebending of the web substrate.

In a conventional “Chemical Vapour Deposition” (CVD) processes therequired process temperatures on the surface to be coated are relativelyhigh. The thermal energy is supplied from the outside. Additionalthermal energy may be released by the chemical reaction. High processtemperatures, however, may damage the web substrate.

One method for coating web substrates is the so-called “Plasma EnhancedChemical Vapour Deposition” (PECVD) process. In this chemical processthe web substrate is exposed with its surface to be coated to a processgas mixture which contains one or more volatile precursors. A volatileprecursor is in particular a precursor gas. The volatile precursors areenergized into a plasma generated by a plasma source. As a result, theexcited precursors react and/or decompose on the web surface, e.g. toproduce a desired deposit/coating. In order to form a silicon oxidelayer a precursor can for example be an organosilicon compound.

A Plasma Enhanced Vapour Deposition (PECVD) process utilizes a plasma toenhance chemical reaction rates of the precursors. As a result, PECVDprocessing allows a treatment, e.g. a deposition/coating, at lowertemperatures. As a consequence the thermal stress on the web substrateis reduced.

The lower temperatures in a PECVD process also allow the deposition oforganic coatings, such as plasma polymers.

In the PECVD process the thermal energy is released by the accelerationof electrons in the plasma. In addition to the formation of radicals bythis process also Ions are formed in the plasma which, together with theradicals, are responsible for the deposition on the web surface.Generally, the gas temperature in the plasma only amounts about a fewhundred degrees Celsius. However the temperature at the surface of theweb substrate to be coated is much lower.

As a plasma forming method for a plasma CVD apparatus, there is knownthe so called capacitively coupled plasma (CCP) technology. In the CCPtechnology, a high frequency voltage is applied to two electrodesopposed to each other thereby forming a plasma between the electrodes.

The patent publication U.S. Pat. No. 7,806,981 discloses a device andmethod for continuously coating a web substrate in a PECVD process. Thedevice comprises a coating station with a vacuum chamber and within thevacuum chamber a rotating drum which supports and transports the websubstrate and which forms a counter-electrode. The device furthercomprises a plurality of magnetron electrodes on the periphery of therotating drum, which form the counter-electrode. The magnetronelectrodes are facing the web. The device further comprises means forsupplying a process gas to the space between the rotating drum and themagnetron electrodes. The magnetron electrodes are powered with analternating voltage at 40 kHz. The magnetron electrodes produceelectromagnetic waves in the microwave range by means of which a plasmais produced between the rotating drum and the magnetron electrodes.

The Magnetron-Technology has numerous limiting factors. A“Magnetron-Drum” arrangement allows only one single coating step. Toincrease the number of layers and/or the coating thickness on a websubstrate several “Magnetron-Drum” arrangements have to be placed in aprocess line one after another. This, however, is very space consuming.

Furthermore a “Magnetron-Drum” arrangement allows only a coating on onefree surface side of the web substrate. The opposite side of the websubstrate rests on the rotating drum and thus cannot be coated.

A further drawback is the quality of the coating. If the magnetronelectrodes are operated at high power voltages, thicker coatings areachieved with the same process speed. However, as a drawback, thepinhole rate in the coating increases and accordingly the quality of thecoating decreases nevertheless.

A further drawback is the process speed which is limited by the designof the device.

The process speed can only be increased with a larger drum which allowsan increase of the circumferential treatment surface. However, a largerdrum diameter is space consuming. Furthermore, as the drum needs to beinside a vacuum chamber, the construction of an installation with alarger drum is more complex and accordingly also expensive.

Further drawbacks are the costs for purchasing, operating andmaintaining such a device.

A further known plasma forming method in a plasma CVD apparatus is theso called inductively coupled plasma (ICP) technology. In the ICPtechnology a high frequency power is supplied to a coil to thereby forman electromagnetic field and thus an induction electric field togenerate a plasma. This system does not contain a counter-electrode asit is the case in the CCP technology.

The patent publication US 2008/0102222 A1 discloses an inductivecoupling type plasma apparatus for continuously coating a web substratecomprising an (induction) coil to which a high frequency (RF) power issupplied.

The patent publication EP 1 020 892 A1 also discloses an apparatus forthe deposition of coatings on a substrate using a magnetically confinedplanar inductively coupled plasma source. Here as well, the plasma isexcited by an (induction) coil to which a high frequency (RF) power issupplied.

In the above mentioned ICP systems the induction coil is underatmospheric condition separated from a vacuum chamber in which theplasma is generated.

Accordingly, a dielectric window has to be provided between the coil andthe substrate to be coated. The dielectric window separates theevacuated film formation space from the atmospheric pressure space in anairtight fashion, with the coil being installed in the atmosphericpressure space, but which allows the transmittance of the high frequencyelectric field into the film formation space.

Furthermore, the above described ICP systems require a faraday shieldarranged between the coil and the substrate to be coated in order toscreen out the plasma from the capacitive electric field of the coil.I.e. in the above mentioned ICP systems the faraday shield is necessaryto obtain an inductive coupled plasma (ICP). The faraday shielddecouples the capacitive (CCP) effect from the inductive effect and thusavoids e.g. self bias.

The faraday shield is combined with the dielectric window in order toenable the ignition of an inductively coupled plasma in the processchamber by letting the electromagnetic field from the coil pass through.For igniting the inductive plasma, there is a capacitive field passageneeded. At steady state, for maintaining the plasma, only induction isneeded. The faraday shield and the dielectric window, are togetherforming an assembling unit.

The patent publication EP 2 396 804 B1 discloses a device for the largearea plasma processing by means of ICP technology as well. However, theantenna concept of the corresponding device substantially differs fromthe induction coils as mentioned above, so that different effects areachieved than with the conventional ICP technology mentioned above.

The corresponding device, however, is only designed for a surfacetreatment, in particular coating, of piece goods as e.g. flat panels,solar cells or semiconductor wafer.

It is now an object of present invention to provide a device and methodto treat and in particular to coat the surface of a web substrate in acontinuous process with high process speed.

Another object of the invention is to provide a device and method totreat and in particular to coat the surface of a web substrate in acontinuous process wherein the construction of the treatment station ofthe device is compact and space saving.

Another object of the invention is to provide a device and method tocoat the surface of a web substrate in a continuous process to producehigh quality coatings, particularly to produce a uniform surfacecoating.

Another object of the invention is to provide a device and method totreat and in particular to coat the surface of a web substrate in acontinuous process wherein the web substrate can be treated and inparticular coated simultaneously or successively on both sides in oneprocess sequence. In one process sequence particularly means in onepass.

Another object of the invention is to provide a device and method toapply a multi-layer coating on the web in a continuous process in oneprocess sequence.

Another object of the invention is to provide a device and method totreat and in particular to coat the surface of a web substrate in acontinuous process which allows the arrangement of a plurality oftreatment stations along a single process line in a space saving manner.

At least one object is achieved with the device and the method asdefined by the claims.

The plasma treatment unit contains at least one extensive antenna and atleast one radiofrequency (RF) generator for exciting said extensiveantenna to at least one of its resonant frequencies, wherein thetransporting system in the process chamber defines a treatment pathsection for the web substrate, wherein the treatment path section forthe web substrate lies opposite to the extensive antenna.

The treatment path section for the web substrate lies in particularspaced from the extensive antenna.

The plasma enhanced process according to present invention is inparticular a “Plasma Enhanced Chemical Vapour Deposition” (PECVD)process as described further above.

The Radio Frequency (RF) Generator is in particular a device forsupplying continuous or pulsed radio frequency power at one or severalfrequency to the extensive antenna in order to establish and maintain aplasma zone.

In a preferred embodiment the RF Generator supplies pulsed radiofrequency power at one or several frequency to the extensive antenna.

Optionally, a matching network can be provided which interconnects theRF generator and the extensive antenna. Thereby radio frequencyreflections at the RF generator output can be avoided and thus anoptimal transfer of radio frequency energy from the RF generator to theextensive antenna can be ensured.

An extensive antenna means an antenna with two-dimensionalcharacteristic. I.e., the antenna has a length and breadth which is muchlarger then its height or thickness, respectively.

In a preferred embodiment of present invention the extensive antenna isa plane antenna. The term “plane” can in particular be understood as asynonym of “planar”. The plane antenna is also called flat-bed antenna.

A continuous web substrate treatment in particular means that the websubstrate is continuously transported through the plasma zone of the atleast one active treatment station.

The plasma zone is formed above the surface of the web substrate to betreated. The plasma zone is in particular planar. The plasma zone is inparticular parallel to the extensive antenna.

The length of the plasma zone in process direction and accordingly thelength of the treatment path section within the plasma can e.g. be 0.2to 1 m. A scale up of the length of the plasma zone up to several metersis also possible.

In order to scale up the length of the plasma zone, in particular withina common process chamber, either the length dimension of the antenna isincreased or several antennas are provided and arranged side by side toform a continuous plasma zone over its length.

Of course the total length of the plasma zone in the device, and inparticular within a common process chamber of the device, can also beincreased by providing several plasma treatment units in succession,each forming a plasma zone within the device. In this case the plasmatreatment units are separated from each other in process direction anddo not form a continuous plasma zone together.

The width of the plasma zone is preferably adjusted to the width of theweb substrate to be treated. In order to determine the width of theplasma zone either the width dimension of the extensive antenna isadjusted or several antennas are provided and arranged side by side toform a continuous large area plasma zone over the entire width.

The treatment process can be a surface etching process, a depositionprocess, i.e. coating process, a surface cleaning process, a surfaceactivation process, a surface modification process or a surfacefunctionalisation process.

The surface modification process and the surface functionalisationprocesses can be a pre-treatment process for a subsequent coating. Thepre-treatment process can in particular be a cleaning of the surface tobe coated. The process gas for such a pre-treatment can e.g. be argonnitrogen, oxygen or a mixture of two or more of the listed gases.

However, one treatment process is in particular a coating process.Accordingly, the treatment station is in particular a coating station.

A coating in particular comprises the deposition of an oxide on thesurface of the web substrate. The oxide can be SiO_(x) (e.g. SiO₂),SiO_(x)C_(y)H_(z), Al_(x)O_(y) (e.g. Al₂O₃) or Si_(x)N_(y) (e.g. Si₃N₄).A coating can also comprise the deposition of a mixture of two or moreof the above mentioned oxides (e.g. SiO_(x)/Al_(x)O_(y)). “X” and “Y”are natural numbers in the range of 1 or higher.

The oxide is or contains in particular silicon oxide using a process gascomprising an organosilicon compound and oxygen. Such an oxide coatingforms in particular a barrier layer.

The coating can also comprise or consist of DLC. DLC is a Diamond-LikeCarbon which defines a class of amorphous carbon material that displayssome of the typical properties of diamond. In this case preferably ahydrocarbon gas, as e.g. acetylene or methane, is used as process gasfor producing the plasma.

The coating can have a thickness of 1 to 1000 nm, in particular of 1 to500 nm.

The plasma treatment unit in particular further contains a separationsurface which physically separates the extensive antenna from theenvironment, in particular from the plasma zone.

The separation surface in particular serves for avoiding a parasiticcoating of the extensive antenna, which would be exposed to the plasmazone without separation surface.

The separation surface is in particular parallel to the extensiveantenna.

It is possible that the plasma treatment unit forms a separation surfaceon both sides of the extensive antenna, in case that on both sides ofthe extensive antenna a plasma zone is formed. I.e. the extensiveantenna is sandwiched between a first and second separation surface orplasma zone respectively.

Accordingly, on both sides of the antenna an individual web substratecan be treated. Each web substrate is passing one of the opposed plasmazones.

It is also possible that the same web substrate passes the plasma zoneson both sides of the antenna, and accordingly is treated twice. For thispurpose the web substrate is deflected along its transporting path bydeflection means as e.g. deflection rollers. In dependency of thedeflection, the same web surface can be treated twice or both oppositeweb surfaces can be treated once.

In case of a plane antenna the separation surface is a separation plane.

The separation surface can be formed by a dielectric cover plate. Thedielectric cover plate can be part of a plasma source assembly. Thecover plate is in particular arranged parallel to the extensive antenna.

The cover plate can be made of glass, a ceramic material or a polymericmaterial. The cover plate can also be made of a mixed material. Theseparation surface is in this case arranged between the web substrate,i.e. the treatment path section for the web substrate, and the extensiveantenna.

The dielectric cover plate shall e.g. protect the antenna from anyinteractions with the plasma to avoid contamination and etching of thesensitive electronic parts of the antenna, such as capacitors.

According to another embodiment of the invention the separation surfaceis formed by the web substrate itself, passing along its treatment pathsection past the extensive antenna. In the latter case, the plasma zoneis formed on the side of the web substrate which is facing away from theextensive antenna.

In this case the web substrate has in particular the same function asthe dielectric cover plate described above.

The treatment path section runs in particular parallel to the extensiveantenna of the plasma treatment unit. The treatment path section runs inparticular parallel to the separation surface of the plasma treatmentunit.

In case of a plane antenna the treatment path section is in particularstraight. As a result the web substrate running through the treatmentpath section defines a plane treatment surface. Accordingly, the websection passing through the treatment path section is plane.

According to a first embodiment of the invention the extensive antennais arranged within the process chamber. In particular, the extensiveantenna is arranged within the environment of the process chamber.

In this case a dielectric window having a certain strength andaccordingly also thickness in order to separate the process chamber froman atmospheric pressure space in an airtight fashion is no longernecessary.

With the ICP system according to present invention no decoupling of aninductive effect from a capacitive effect is necessary. Accordingly, thepresence of a faraday shield and a dielectric window separating theantenna from the web substrate to be treated is not necessary with thepresent invention.

This allows the placement of the antenna within the environment of theprocess chamber as mentioned above.

Accordingly, a better electrical energy coupling between the inductivesystem and the plasma without losses in the dielectric window isachieved. As a result, the plasma density and the plasma homogeneity ishigher. Hence there is less machine maintenance and higher productivity.

Further, without dielectric window no parasitic coating deposition thatcontaminates the dielectric window occurs.

If now the coil of the ICP system according to above mentioned state ofthe art would be placed within the process chamber without dielectricwindow and faraday shield, the system would produce a capacitive coupledplasma by a high radio frequency (RF) voltage applied to the coil.Accordingly, the plasma would be quite weak. An inductive effect wouldonly be achieved by means of a huge current injected into the coil.

According to a further development of the first embodiment at least twoseparate plasma zones are arranged within a common process chamber, inparticular within a common low pressure environment of the processchamber.

The at least two separate plasma zones can be formed by a commonextensive antenna or treatment unit respectively or by at least twoindividual extensive antennas or treatment units respectively.

In the latter case, the at least two extensive antennas are arrangedwithin the common process chamber, in particular within a common lowpressure environment of the process chamber.

Common process chamber means that the low pressure space of the processchamber in which the antennas are arranged is interconnected.Accordingly, the low pressure in the common process chamber is generatedby a common pumping system.

In particular, each of the extensive antennas forms a separate plasmazone within the process chamber.

In particular, each of the extensive antenna is powered independently bymeans of at least one radiofrequency (RF) generator.

The at least two antennas within the common process chamber andaccordingly the plasma zones can be arranged in series along theconveying path of the web substrate through the process chamber.

The at least two antennas within the common process chamber andaccordingly the plasma zones can be arranged on both sides of theconveying path of the web substrate through the process chamber.

The at least two antennas within the common process chamber andaccordingly the plasma zones can be arranged in parallel with respect tothe conveying path of the web substrate.

I.e. the at least two antennas within the common process chamber andaccordingly the plasma zones are arranged opposite to each other on bothsides of the web substrate. Between them the conveying path of the websubstrate is arranged. In this case the web substrate separates the twoplasma zones from each other.

The at least two antennas within the common process chamber can bedesigned for successive treating, in particular coating, the samesurface of the web substrate. I.e. the treating of the surface iscarried out in two or more successive steps in one pass within thecommon process chamber.

A successive coating can be the formation of one coating layer in two ormore steps. The successive coating can be the formation of two or morecoating layers above each other (multi-layer deposition).

The at least two antennas within the common process chamber can bedesigned for simultaneous or successive treating, in particular coating,the two opposite surfaces of the web substrate.

The above disclosed solutions can be combined with each other, ofcourse. I.e. both surfaces of the web substrate can be treated whereasat least one surface is subjected to at least two successive treatmentsteps in the common process chamber.

The web substrate is guided through the process chamber passing theplasma zones of the antennas within the process chamber.

According to a further development of present embodiment at least twoindividual web substrates are guided through a common process chamberpassing a plasma zone.

In particular, the at least two individual web substrates pass theplasma zone(s) parallel to each other.

The at least to individual web substrates can pass a common plasma zone,which is e.g. enclosed by the at least two individual web substrates.

The at least two individual web substrates can pass separate plasmazones.

The separate plasma zones can be formed by a common antenna, e.g. onboth sides of the antenna.

The separate plasma zones can also be formed by individual antennas.

Individual web substrates in particular means that the web substratesare individually unwound from separate rollers.

Individual web substrates in particular means that the web substratesare individual rewound on separate rollers.

According to a second embodiment the extensive antenna is arrangedoutside the process chamber.

However, in any case the extensive antenna is designed and arranged suchthat the plasma zone lies within the process chamber.

In the second embodiment the separation surface can be formed by adielectric wall section of the process chamber. In this case theextensive antenna and the plasma zone, which is always arranged in theprocess chamber, are physically separated by the dielectric wallsection.

According to a specific embodiment of present invention the planeantenna is vertically aligned.

Accordingly, the treatment path section is in particular alignedvertically. The process direction can be bottom up. The processdirection can be top down.

According to another specific embodiment of present invention the planeantenna is horizontally aligned.

Accordingly the treatment path section is in particular alignedhorizontally.

According to another specific embodiment of present invention the planeantenna is arranged in an inclined manner.

The treatment process is a roll-to-roll process. The transporting systemin particular contains a drive for driving the rewind roller. Thestarting point of the continuous treatment process is in particular theunwind roller and the end point of the continuous treatment process isin particular the rewind roller.

The transporting system can contain a drive for driving the unwindroller. The transporting system can contain a drive to drive at leastone span roller.

According to an embodiment of the invention the transporting systemcontains a first and a second span member which are spaced from eachother. The span members define in between a free span for the websubstrate. The free span in particular contains the treatment pathsection for the web substrate. Such a lay-out allows a free spantreatment of the web substrate.

“Free span” in particular means that the treatment path section isdefined by the span members, which lie outside the treatment pathsection and not by a support member supporting the web substrate in thetreatment path section.

In this embodiment the plasma zone is located in the area of the freespan between the span members.

The span member can be a deflection member, which defines a deflectionpath for the web substrate. The span members are e.g. rollers, inparticular deflection rollers. The web substrate is in particular guidedalong the circumference of the rollers and thereby deflected.

Span rollers and/or deflection rollers of the transporting system canalso be designed for acting as cooling rollers.

The transporting system can contain at least one tensioning memberacting on the web substrate for tensioning the web substrate along thetreatment path section. The tensioning member can contain a restoringelement which generates a restoring force to the tensioning member sothat a tension force is exerted on the web substrate.

The transporting system can in particular contain a tension controlsystem with tensioning members for automatically control the tension ofthe web substrate along its process path.

The span member can be designed as a tensioning member, which exerts atension force on the free span of the web substrate.

For the sake of completeness, it is mentioned that the span members canalso be formed by the unwind and rewind roller which accommodate the websubstrate to form coils.

In an embodiment of the invention the treatment path section of the websubstrate and thus the web substrate in the process runs at a distancefrom the separation plane so that the plasma zone is formed between thetreatment path section of the web substrate and the separation plane andthus the plasma produced in the plasma zone is confined between the websubstrate and the separation plane. Said distance can be e.g. 10 to 100mm, in particular 30 to 80 mm.

In another embodiment of the invention the treatment path section of theweb substrate, and thus the web substrate runs close to the separationsurface or forms the separation surface so that the plasma zone isformed on the side of the web substrate which is facing away from theextensive antenna. The distance to the separation surface can be e.g.only 1 mm to 10 mm, in particular 1 mm to 5 mm.

In a further development of said embodiment a first treatment pathsection of the web substrate runs close to the separation surface orforms the separation surface as described above. Said distance can bee.g. 1 mm to 5 mm. Further, a second treatment path section runs at adistance to the separation surface and the first treatment path section.Said distance can be e.g. 10 to 100 mm, in particular 30 to 80 mm. Inthis configuration the plasma zone is formed between the first andsecond treatment path section of the web substrate and thus the plasmaproduced in the plasma zone is confined between two web substratesections. Such a configuration avoids parasitic coatings of deviceparts.

With respect to the process direction, a deflection member can bearranged between the first and second treatment path. The deflectionmember defines a deflection path for the web substrate. Thus, in theprocess the web substrate is deflected from the first treatment pathsection into the second treatment path section or vice versa.Accordingly, the web substrate in the second treatment path section runsin particular in opposite direction to the web substrate in the firsttreatment path section. The two treatment path sections run inparticular parallel to each other.

According to an embodiment of the invention the plasma treatment unitcontains a bias electrode arrangement with a bias electrode. The biaselectrode is made of an electrical conductive material, in particularmetal.

The bias electrode is arranged opposite and at a distance to the planeantenna, in particular a plasma source assembly as described furtherbelow. The bias electrode is in particular extensive, e.g. plane. Thebias electrode can be a flat-bed assembly. The bias electrode runs inparticular parallel to the plane antenna.

The bias electrode is powered by an RF generator. Optionally, a matchingnetwork can be provided which interconnects the RF generator and thebias electrode. Thereby radio frequency reflections at the RF generatoroutput can be avoided and thus an optimal transfer of radio frequencyenergy from the RF generator to the bias electrode can be ensured.

The bias electrode can extend over the whole area of the plane antenna.The bias electrode can also extend only over a part of the area of theplane antenna as viewed in process direction.

The web substrate is transported along a treatment path section betweenthe plasma source assembly and the bias electrode.

The treatment station contains a feed passage opening for in particularcontinuously feeding the web substrate into the process chamber.Further, the treatment station contains a discharge passage opening for,in particular continuously discharging the treated web substrate fromthe process chamber. The openings are in particular slit-shaped with alarge ratio of the depth of the slit to the width of the slit in orderto avoid a significant gas flow into the process chamber. This allowsthe control of a low gas pressure in the process chamber.

The treatment station further contains a gas supply system for supplyinga process gas to the plasma zone in the process chamber. The process gascan be fed from the side, e.g. between the separation surface and theweb substrate. The feature “process gas” also comprises a process gasmixture.

The gas supply system in particular contains gas injection members forfeeding the process gas into the plasma zone. The gas supply system cancontain diffuser members for distributing the process gas in the plasmazone.

The process chamber means a chamber where the plasma process takes placeand the web substrate is treated, in particular coated.

The process chamber is in particular a low pressure or vacuum chamber,respectively.

The treatment station further contains a pumping system for removinggaseous components from the process chamber.

The pumping system serves in particular for establishing (producing andmaintaining) a low pressure (also called under pressure or vacuum)within the process chamber. The term “low pressure” is meant in thecomparison to the ambient pressure, in particular to the atmosphericpressure. The low pressure can e.g. amount a few Pascal (Pa), as e.g. 5Pa. I.e., the process chamber is in particular a vacuum chamber.

The pumping system can also serve to pump volatile by-products producedduring the reactions from the process chamber. In this connection thepumping system also has the function of an exhaust system.

The plasma treatment unit according to the first aspect of presentinvention does not contain a rotating drum anymore. In contrary, thedesign of the antenna is plane so that the plasma treatment unit can bedesigned compact and thus place saving. This gives a high flexibility inthe design of the device with respect to the treatment of the websubstrate. I.e. the device can be designed and configured to suit theneeds of the customer.

The device can contain in particular two or more treatment stations.

The two or more treatment stations can form process chambers which areindependent from each other with respect to the establishing of a lowpressure in the process chamber.

However the process chambers of the two or more treatment station canalso be coupled with this respect.

A first treatment station is in particular a pre-treatment station toprepare the surface of the web substrate to a subsequent coating.

According to an embodiment, the device contains at least two treatmentstations arranged in series with respect to the process direction forcarrying out the same treatment process. As a consequence the plasmazone and hence the treatment area is increased, in particularmultiplied, in process direction.

In fact, such a pre-treatment station can be combined with aconventional capacity coupled magnetron device.

According to a specific embodiment, the device contains a firsttreatment station with at least one plasma treatment unit. In the firsttreatment station the web substrate surface is e.g. pre-treated for asubsequent coating. However, the first treatment station can also be afirst coating.

The device further contains a second treatment station with at least oneplasma treatment unit. The second treatment station is e.g. a coatingstation for coating or further coating the e.g. pre-treated surface ofthe web substrate, e.g. with a barrier layer. The at least one secondtreatment station is arranged subsequent to the first treatment stationin process direction. The process direction generally corresponds to thetransport direction of the web substrate.

In this connection, the device according to the present invention issuitable for a modular layout. The device can e.g. be built from severalmodules. One or more than one modules contain at least one treatmentstation according to the invention.

The modules can be combined in a successive arrangement with respect tothe process direction.

So, the above mentioned first treatment station can be part of a firstmodule. The above mentioned second treatment station can be part of asecond module.

In a further development of the modular concept the device contains abase module. The base module contains a unwind and rewind roller and inparticular also the drives to drive the rollers. The base module can bean indispensable component of the modular design.

Further, the base module can also comprise a first treatment station,e.g. for a pre-treatment of a surface of the web substrate to be furthertreated, e.g. coated. This in the light of the fact, that the websubstrate basically has to be pre-treated before applying furthertreatments as e.g. a coating, on the web substrate.

Further, the device can contain one or more treatment module asdescribed above. The treatment module(s) are arranged subsequent to thebase module in process direction.

According to a specific embodiment of the invention the modules of thedevice can be arranged atop each other. This can be the case inparticular when the antenna and accordingly the treatment path sectionsare aligned vertically. If a base module is provided, the base modulecorresponds to the base of the device.

The device can be terminated at the top by a top module. The top moduleis in every case arranged above the base module, if provided. The topmodule is in particular arranged atop a treatment module. The top modulein particular contains at least one deflecting member.

Independent of the above described modular concept, the device accordingto a specific embodiment can contain at least two process sections,wherein to each process section at least one plasma treatment unit fortreating the web substrate is allocated. “Process section” means asection in the device where the web substrate is treated. I.e., eachprocess section comprises at least one plasma treatment unit.

The process direction in one process section is bottom up. The processdirection in the other process section is top down. I.e., the websubstrate is treated in the bottom up process direction of the firstprocess section and in the top down process direction of the secondprocess section as well.

Between the two process sections, at least one deflection member, e.g. adeflection roller, is arranged to deflect the web substrate from thebottom up direction into the top down direction or vice versa.

The at least one deflecting member is in particular arranged above thetreatment station(s) or above the treatment modules, respectively.

The at least one deflecting member can be part of a deflecting module.The deflecting module can correspond to the top module as describedabove.

In an embodiment of the invention on both sides of the treatment pathsection of the web substrate a plasma treatment unit with a planeantenna is arranged. The plasma treatment units are lying opposite toeach other and are spaced from the treatment path section. Between thetreatment path section of the web substrate and the plane antenna, inparticular the separation plane of the plasma treatment unit, in eachcase a plasma zone is formed, so that both sides of the web substratecan be treated simultaneously.

Accordingly, the in particular straight path section runs between twoplane antennas. The plasma treatment units are in particular placed in acommon process chamber of a treatment station.

The plane antennas can be supplied by a common or by separate RFgenerators.

In an embodiment of the invention the device contains a first treatmentstation and arranged in processing direction subsequent to the firsttreatment station a second treatment station. The transporting system isdesigned such that the web substrate first can be transported throughthe first treatment station and subsequently through the secondtreatment station in a continuous manner and in particular in one pass.

The first treatment station can be part of a first treatment module andthe second treatment station can be part of a second treatment module.It is also possible that both treatment stations are part of a commontreatment module.

The web substrate is in particular transferred between the two treatmentstations through feed and discharge passage openings as described above.The feed and discharge passage openings can form process interfacesbetween modules.

In an embodiment of the invention in processing direction between theplasma treatment unit of a first, preceding treatment station and theplasma treatment unit of a second, subsequent treatment station at leastone deflection member is arranged, which deflects the web substrate suchthat the transporting direction of the web substrate through the plasmazone of the plasma treatment unit of the second treatment station isopposite or in an angle to the transporting direction of the websubstrate through the plasma zone of the plasma treatment unit of thefirst treatment station.

In this case the first and second treatment stations are in particularpart of a common treatment module. The two transporting directions canin particular be bottom up and top down as mentioned further above.

The at least one deflection member is in particular arranged outside theprocess chambers of the preceding and subsequent treatment station. Theat least one deflection member can be a deflection roller. The at leastone deflection member can be part of a deflection module.

According to another further development of the present invention theextensive antenna as e.g. described above is combined with a rotatabledrum.

The rotatable drum is part of the transporting system. The treatmentpath section of the web substrate is curved and runs along a peripheralsurface section of the rotatable drum. This peripheral surface sectiondefines a curved resting surface for the web substrate in the processchamber.

The antenna is in particular integrated in a plasma source assembly asdescribed further below.

In this development the web substrate is treated in a roll-to-rollprocess as well. I.e. the device contains an unwind roller at thebeginning of the process path and a rewind roller at the end of theprocess path.

Such an arrangement is characterised in that in operation the websubstrate, in the region of the formed plasma zone, rests on a curvedcircumferential treatment surface area of the rotatable drum. The websubstrate is in particular transported at the rotation speed of therotating drum, while being treated, in particular coated.

The plasma zone is arranged in a process chamber, which is in particulara low pressure or vacuum chamber.

According to a first embodiment of this further development theextensive antenna is plane. The plasma source assembly containing theplane antenna is arranged at a distance to the rotatable drum and facinga curved circumferential surface area of the drum so that a gap isformed between the rotatable drum and the plasma source assembly.

The plasma zone is formed in the space formed by the gap. I.e. Theplasma zone is formed between the plasma source assembly, in particularthe cover plate, and the web substrate resting on the drum. The coverplate facing the drum towards the transporting path of the web substrateis in particular plane as well. The surface of the cover plate forms theseparation surface.

According to a second embodiment the extensive antenna is curved. Thecurved shape of the extensive antenna is in particular adapted to theshape of the curved surface area of a rotatable drum.

Accordingly the cover plate of the plasma source assembly facing the websubstrate is in particular curved as well.

The plasma source assembly with its curved antenna is also arranged at adistance to the rotatable drum and facing a curved circumferentialsurface area of the drum so that a curved gap is formed between therotatable drum and the plasma source assembly.

The plasma zone is formed in the space formed by the gap. I.e. Theplasma zone is formed between the plasma source assembly, in particularthe cover plate, and the web substrate resting on the drum. The coverplate facing the drum towards the transporting path of the web substrateis in particular concave. The surface of the cover plate forms theseparation surface.

The drum according to the above mentioned embodiments can form a biaselectrode as described further above.

According to a third embodiment the extensive antenna is curved as well.The curved shape of the extensive antenna is in particular adapted tothe shape of the curved surface area of a rotatable drum. Accordinglythe cover plate of the plasma source assembly facing the web substrateis in particular curved as well.

In contrast to the second embodiment the plasma source assembly with itscurved antenna is arranged on the rotatable drum. The cover plate facingaway from the drum towards the transporting path of the web substrate isin particular convex.

In this case the plasma zone is formed above the surface of the websubstrate which is facing away from the drum. The web substrate formsthe separation surface.

Generally, one or several of the above described plasma sourceassemblies can be arranged along the curved circumference of therotatable drum in process direction in series.

The extensive antenna is the centrepiece of a large-area plasma source.The plane antenna forms a planar plasma source. The curved antenna formsa curved plasma source.

The extensive antenna comprises a plurality of interconnected elementaryresonant meshes. Each mesh is composed of inductive and capacitiveelements. Each mesh comprises in particular at least two conductive legsand at least two capacitors. This way the antenna has a plurality ofresonant frequencies.

For processing larger areas, a plasma treatment unit can comprise atleast one supplementary extensive antenna.

The patent publication EP 2 396 804 B1 discloses a technology forgenerating a plasma by means of exciting a plane antenna of the abovementioned design by a RF generator to at least one of its resonantfrequencies.

The patent publication EP 1 627 413 B1 discloses the same technology forgenerating a plasma, in this case however, by means of exciting a curvedantenna by an RF generator to at least one of its resonant frequencies.

Present invention corresponds to a particular application of thistechnology. For further details regarding the implementation of saidtechnology it is referred to the mentioned patent publications.

The conductive legs can be parallel to each other. I.e. the legarrangement of the present antenna does not form a coil.

The Radio Frequency (RF) Generator generates high currents in each legas they are not independent. By this, each mesh generates anelectromagnetic field with a more uniform distribution along thelongitudinal axis of the mesh.

At resonant frequency there is a standing current wave propagatingthrough the legs producing a standing electromagnetic field in theprocess chamber which ignites the plasma.

Said resonant frequency can be tuned by an adjustable conductive platedescribed further below.

The legs are e.g. made of copper, in particular copper tubes. The coppertubes may be cooled by cooling liquid, as e.g. water, to preventexcessive heating of the antenna components such as the capacitors.

As mentioned above, in present invention the copper tubes in particularform the legs of the antenna and not a coil as known from the citedstate of the art.

The antenna may contain elementary resonant meshes having two parallellonger conductive legs whose ends are interconnected by transverseshorter connecting elements. Such a design of elementary resonant meshallows effective inter-connections of a plurality of meshes forconstituting a large-area antenna.

Elementary resonant meshes, in particular with parallel conductive legs,are in particular interconnected by common legs for forming a laddershaped resonant antenna. The legs form the ladder spokes. Such a designallows constituting a very large antenna with well defined amplitudedistribution of currents over the whole surface of the antenna.

The design of the antenna is in particular such that each resonantfrequency corresponds to a sinusoidal current distribution in theantenna legs. This is in particular the case if all capacitors have thesame capacitance, and if all the legs are identical (same inductance).

The resonating currents flowing in the antenna legs generate high anduniform electron densities. Accordingly, a plasma is created over alarge surface, having good homogeneity within the whole plasma zone, andacross the large surface.

In an embodiment of the invention the transport direction of the websubstrate is parallel to the conductive legs.

In another embodiment of the invention the transport direction of theweb substrate is at an angle, in particular perpendicular, to theconductive legs. In this configuration the plasma treatment of the websubstrate surface is more uniform.

According to a first embodiment of the antenna, the transverse shorterconnecting elements comprise opposing capacitors.

According to a second embodiment of the antenna, the parallel longerconductive legs comprise opposing capacitors each connected in seriesbetween the lengths of a respective conductive leg.

The longer conductive leg comprises at least one capacitor arrangedbetween at least two lengths of a respective conductive leg.

If the legs are formed by copper tubes, then said lengths of theconductive leg are formed by individual copper tubes.

This embodiment in particular applies in cases where the transportdirection of the web substrate is perpendicular to the conductive legs.

This embodiment allows the reduction of the RF voltage applied to theantenna.

Both embodiments may be combined, wherein first opposing capacitors areconnected within the transverse shorter connecting elements and secondopposing capacitors are connected within the conductive legs.

As the extensive antenna has a plurality of interconnected elementaryresonant meshes, and as the antenna is excited to at least one of itsresonant frequencies, the amplitude distribution of currents in theelementary element meshes of the antenna is stable and can be very welldefined over the whole surface of the antenna.

The distribution of current amplitudes can be controlled by choosingwhich antenna resonant frequency is to be excited by the RF generator.

Resulting from the very well defined current amplitude distribution overthe whole surface of the antenna, a very well defined distribution ofplasma can be created by the antenna of the invention.

Considering that the plasma quickly diffuses from areas with highcurrent intensities to areas with lower current intensities, a moreuniform distribution of plasma can be created by the antenna of theinvention.

The presence of the plasma slightly affects the resonant frequenciesvalues, essentially because of inductive couplings.

In order to compensate the frequency shifts, the plasma treatment unitaccording to the invention can comprise a conductive plate, also calledshield. The conductive plate is in particular arranged parallel to theantenna. The conductive plate is in particular arranged close to theantenna. The conductive plate is in particular grounded. The conductiveplate is in particular made of metal. The conductive plate is arrangedon the side of the antenna which is facing away from the treatment pathsection of the web substrate, i.e. the plasma zone, and the separationsurface respectively.

In an embodiment of the invention the legs, and in particular the coppertubes forming the legs, are embedded in a dielectric material. Thedielectric material has in particular a high thermal conductivity inorder to remove heat from the legs. Further, the dielectric material inparticular gives robustness to the device.

In an embodiment the entire extensive antenna is embedded in adielectric material.

The dielectric material can be a foam.

The dielectric material can be a silicone elastomer. The dielectricmaterial can be made of silica or alumina.

The plasma treatment unit can in particular comprise a plasma sourceassembly with an extensive antenna embedded in a dielectric material.The plasma source assembly can be delimited on the side facing theplasma zone by a dielectric cover plate forming the separation surface.

The plasma source assembly, on the opposite side of the cover plate, canbe delimited by the conductive plate forming a base plate.

The plasma source assembly, on the connecting sides, can be delimited bya frame structure.

In case of a plane antenna, the plasma source assembly is in particulardesigned as flat-bed assembly.

Conductive plate and cover plate run in particular parallel to eachother. Hence, the extensive antenna embedded in the dielectric materialis sandwiched between the cover plate and the base plate.

In an embodiment of the invention means for adjusting the position, inparticular the distance of the conductive plate relative to the antennacan be provided, so that the resonant frequencies of the antenna can be(fine) adjusted. The conductive plate is in particular close to theantenna.

By adjusting the relative position of the conductive plate with theantenna, the resonant frequencies of the antenna can be tuned in orderto correspond to the RF generator excitation frequencies.

Furthermore, by adjusting the relative position of the conductive plate,the wave's energy deposition pattern in the plasma can be influenced,and this can be used as a means for adjusting the boundaries conditionsof the plasma EM normal modes.

However, the conductive plate is not an essential feature of presentinvention as the resonant frequency can also be configured by choosingdifferent capacitors.

If on both sides of the extensive antenna a separation surface is formedwhich, in each case, separates the extensive antenna from a plasma zone,the plasma source assembly can contain a second dielectric cover plateinstead of a conductive base plate.

However, in such an arrangement the separation surface can also beformed in each case by a treatment path section of a web substrate onboth sides of the extensive antenna.

In known inductively coupled plasma sources limitations are met in theattempt of up scaling due to power injection problems (very highcurrent/voltages into the matching elements and the feeding lines).

The resonant antenna according to the invention is in particularcharacterised by a finite and non-reactive impedance. I.e. the presentantenna presents purely real impedance (typically close to 50 Ohm whencoupled to the plasma) and thus independently of the antenna size. Thisenables convenient up-scaling of the plasma source to create a largearea plasma zone, e.g. up to meters of length. Thus, the processedsurfaces can be greatly extended.

This means that the impedance is purely resistive. This is in contrastto CCP or standard ICP systems which have coils as mentioned in theintroduction of the state of the art.

CCP systems for example have an impedance Z=1/A where A is the surfacearea of the electrode. For large surface area, A is Large and Z issmall. Z tends to nil for extremely large surface area. However, if Z issmall very large currents are produced.

On the other hand for standard ICP systems with coils known in the stateof the art the impedance is Z=N*R, where N is the number of turns of thecoil and R is the finite diameter of the coil. For large surfaces areathis leads to very high impedance with low current and very highvoltage.

The antenna according to present invention is in particular resonantwhich means the impedance Z is finite and non reactive. Therefore, onecan expect to build an antenna of almost any size up to several squaremeters.

According to an embodiment, the treatment station according to theinvention may further comprise a system for generating a magnetic field,in particular a static magnetic field, in the vicinity of the extensiveantenna. With such a magnetic field plane polarized helicon-like wavescan be excited in the plasma, so that the processing rate of theapparatus is improved.

The magnetic field can be generated by permanent magnets or by DC(direct current) coils.

According to a further development of this embodiment the device maycomprise an array of permanent magnets. The array of magnets is inparticular arranged parallel to the extensive antenna. In case of aplane antenna the array of magnets lies in a plane. The magnets are inparticular arranged on the side of the web substrate in the treatmentpath section facing away from the extensive antenna.

For the sake of completeness it is mentioned that the device may furthercomprise means for injecting a DC (direct current) in said extensiveantenna superposed to the radiofrequency current such that said DCgenerates a magnetic field in the vicinity of the extensive antenna.

The means can comprise a DC generator.

The DC (direct current) is in particular injected into the conductivelegs of the antenna. The antenna can be feed with DC (direct current) atthe end in particular at both ends of each conductive leg.

The DC (direct current) is in particular fed to the conductive legsthrough choke coils.

According to an embodiment, the antenna is fed with at least two phaseshifted RF power signals at two different, i.e. distant, injectionpoints, resulting in a translation with time of the current distributionin the legs of the antenna. In other words, this results in a travellingcurrent distribution. This proceeding is also called “bi-phasedfeeding”. Accordingly, the radio frequency generator is adapted forfeeding the antenna with two phase shifted RF power signals.

Accordingly, the plasma distribution is translated with time over thewhole surface of the antenna. This results in a more uniform processingdistribution, i.e. plasma heating. Furthermore, the travelling currentdistribution enhances strongly the helicon-like wave excitation.

The phase shifted signals can be obtained by combining several RFgenerators. The phase shifted signals can also be obtained by splittingthe signal issued from a single generator with a power splitter and aphase shifter.

Helicon wave discharges are known to efficiently produce high-densityplasma, and have been exploited as a high density plasma tool forsemiconductor processing, as etching, deposition, sputtering.

A helicon wave is a low frequency electromagnetic wave that can exist inplasmas in the presence of a magnetic field.

A helicon discharge is an excitation of plasma by helicon waves inducedthrough radio frequency heating. The difference between a helicon plasmasource and a inductively coupled plasma is the presence of a magneticfield directed along the axis of the antenna. The presence of thismagnetic field creates a helicon mode of operation with higherionization efficiency and greater electron density than a typical ICP(Inductively Coupled Plasma).

The web substrate is a flexible material. Flexible means that the websubstrate can be bent without suffering a structural damage.

The web substrate can be a single-layered or multi-layered film. Amulti-layered film particularly contains a carrier film. Thesingle-layered or multi-layered film particularly contains a polymermaterial or consists of it. In particular at least one layer of amulti-layered film is a polymer film. In an embodiment the web substrateis a multi-layered film with a carrier film made of a polymer material.

The web substrate, i.e. the polymer film or a layer of the polymer film,e.g. the carrier film, can be of polyester, as e.g. a poly(ethyleneterephthalate) (PET), polybutyleneterephthalate (PBT) orpolyethylenenaphthenate. The web substrate or film can also be ofpolyalkene, as e.g. polyethylene (PE), polypropylene (PP) orcyclo-olefine (co)polymer. The web substrate or film can also be ofpolyamide (PA), ethylvinylalcohol (EVOH) or liquid-crystal polymer(LCP). The web substrate or film can also be of halogenated plastic ase.g. polyvinyl chloride (PVC) or polyvinylidene chloride (PVDC).

The invention also concerns a method for continuously treating a websubstrate in a plasma enhanced process with a device as described above.The method contains the steps of:

-   -   providing a web substrate with a first web end section which is        placed on an unwind roller and with a second web end section        which is placed on a rewind roller and with an intermediate web        section;    -   generating a plasma in the plasma zone of the plasma treatment        unit in the treatment station;    -   in particular continuously, unwinding the web substrate from the        unwind roller and, in particular continuously, rewinding the web        substrate by the rewind roller, thereby    -   in particular continuously, transporting an intermediate web        section of the web substrate along the treatment path section in        the at least one treatment station through the plasma zone of        the plasma treatment unit and thereby plasma treating a surface        of the web substrate.

The device according to the invention has at least one of the followingadvantages:

-   -   due to the high uniformity of the generated plasma the treatment        a high quality surface treatment and in particular coating is        achieved;    -   the device enables a continuous treatment of a web substrate        particularly without edge effects;    -   the device enables a large area treatment of a web substrate;    -   the device enables a simultaneously treatment, particularly a        coating, on both sides of the web substrate;    -   the device enables a multi-layer coating on the web substrate in        one process sequence;    -   the device enables a sequence of similar or different treatments        on the web substrate in one process sequence;    -   the device can be designed in a space-saving manner even if        several plasma treatment stations for the web substrate are        provided within the device;    -   the design of the device is simple;    -   the invention allows a modular setup of the device. Thus, a        single device can be adapted to different needs for web        treatment;    -   the device can be operated at higher line speed (transportation        speed of the web substrate), e.g. at 400 m/min (meter per        minute). Due to a place saving arrangement of the plasma        treatment stations, the invention allows the arrangement of two,        three or even more treatment stations in series carrying out the        same treatment process in order to double, triple, etc. the        plasma zone in process direction. As a consequence a doubling        (800 m/min) or triplication (1′200 m/min), etc. of the        transportation speed is achieved;    -   due to high density of the generated plasma, the device can be        operated at higher deposition rates for barrier coatings. The        dynamic growth rate can e.g. be 2 um/min (micrometer per        minute);    -   the plasma treatment unit does not contain moving parts, as e.g.        rotating electrodes;    -   the device produces an inductive coupled plasma and does not        have to contain an electrode/counter-electrode arrangement as it        is the case with a capacitive coupled plasma with magnetron        technology. The power is rather inductively coupled to the        plasma;    -   there is no plasma arcing, which can cause pinholes in the        polymer film;    -   the web substrate has not to be supported by a support during        the treatment;    -   the waste of web substrate is reduced as only setup waste        accrues but not trimming waste. An edge trimming is not        necessary;    -   the inductive coupled plasma generation technology according to        present invention does not limit the dimension of the plasma        zone. I.e. there are no technology-based restrictions with        regard to an up-scaling.

Features which are disclosed in connection with a formulation as “inparticular” are to be considered as optional features of presentinvention.

Exemplified embodiments of the device according to the invention aredescribed in connection with the following figures. The figures showschematically:

FIGS. 1a and 1b a first embodiment of elementary mesh for the planeantenna, and the equivalent electric circuit thereof;

FIG. 1c illustrates a high pass antenna with a series of elementarymeshes according to the first embodiment;

FIGS. 2a and 2b a second embodiment of elementary mesh for the planeantenna, and the equivalent electric circuit thereof;

FIG. 2c a low pass antenna with a series of elementary meshes accordingto the second embodiment;

FIGS. 3a and 3b a third embodiment of elementary mesh for the planeantenna, and the equivalent electric circuit thereof;

FIG. 3c a hybrid antenna with elementary meshes according to the thirdembodiment;

FIG. 4 a first embodiment of a device according to the invention;

FIG. 5 a second embodiment of a device according to the invention;

FIG. 6a a third embodiment of a device according to the invention;

FIG. 6b a cross section of the web substrate treated with the deviceaccording to FIG. 6 a;

FIG. 7a a fourth embodiment of a device according to the invention;

FIG. 7b a cross section of the web substrate treated with the deviceaccording to FIG. 7 a;

FIG. 8 an embodiment of a treatment station according to the invention;

FIG. 9 a further embodiment of a web run in a treatment stationaccording to the invention;

FIG. 10 a further embodiment of a web run in a treatment stationaccording to the invention;

FIG. 11 an embodiment of a plasma source assembly according to theinvention;

FIG. 12 an assembly draft of a specific embodiment of a device accordingto present invention;

FIG. 13 a first embodiment of a plasma treatment unit with a rotatabledrum;

FIG. 14 a second embodiment of a plasma treatment unit with a rotatabledrum;

FIG. 15 a further embodiment of a treatment station according to theinvention;

FIG. 16 a further embodiment of a treatment station according to theinvention.

According to the invention, a plane antenna with a plurality ofelementary resonant meshes is provided as a source for generating largearea plasmas.

FIGS. 1, 2 and 3 show three embodiments for such an elementary mesh M1and the corresponding equivalent electric circuit E1.

Each elementary mesh M1 has two parallel longer conductive legs 1 and 2whose ends are interconnected by transverse shorter connecting elements3 and 4. The longer connecting legs 1 and 2 act essentially as inductivecomponents. Each elementary mesh has at least two opposing capacitors 5and 6 (FIGS. 1a, 2a, 3a ).

In the high pass mesh of FIG. 1, the opposing capacitors 5 and 6constitute said shorter connecting elements 3 and 4.

In the low pass mesh of FIG. 2, the opposing capacitors 5 and 6 are eachconnected in series between two lengths 1 a, 1 b or 2 a, 2 b of arespective conductive leg 1 or 2.

In the pass band mesh of FIG. 3, two first opposing capacitors 5 and 6constitute said shorter connecting elements 3 and 4, and two secondcapacitors 5 a and 6 a are each connected in series between two lengths1 a, 1 b or 2 a, 2 b of a respective conductive leg 1 or 2.

Each elementary mesh forms a resonant L-C loop as shown on thecorresponding equivalent electric circuits E1 (FIGS. 1b, 2b, 3b ).

Several elementary meshes are interconnected in order to form a planeantenna of the desired dimensions.

For instance, FIG. 1c shows a high pass antenna 9.1 (generally named: 9)made of a series of elementary high pass meshes M1, M2, M3 according toFIG. 1b , interconnected to form a ladder-shaped resonant antenna.

FIG. 2c shows a low pass antenna 9.2 made of a series of low pass meshesM1, M2, M3 according to FIG. 2b , interconnected to form a ladder-shapedresonant antenna.

FIG. 3c shows a hybrid antenna 9.3 made of a series of elementary meshesM1, M2, M3 according to FIG. 3b , interconnected to form a ladder-shapedresonant antenna.

In all three embodiments, adjacent meshes such as meshes M1 and M2 havea common conductive leg 2.

If N is the number of legs of the antenna, said antenna presents N−1resonant frequencies.

The values of these resonant frequencies depend on the geometry of thelegs 1, 2 (length, diameter, distance between two adjacent legs . . . )and on the values of the capacitors 5, 6.

The antenna can be operated at e.g. 50 kW and 13.56 MHz.

If all capacitors 5, 6 have the same capacitance, and if all the legs1,2 are identical (same inductance), each resonant frequency correspondsto a sinusoidal current distribution in the antenna legs such as legs1,2, as shown for instance on FIG. 7 of EP 2 396 804 B1.

When excited at a resonant frequency, the antenna produces anelectromagnetic (EM) field pattern with a very well defined sinusoidalspatial structure. This allows a great control on the excitation of EMnormal modes in the plasma (normal mode=eigenfunction). The antenna willalways be excited (or fed) at one, or several, of its resonantfrequencies.

A large variety of EM waves can be excited in plasmas. Certaincategories of waves can only exist if the plasma is magnetized, as forexample helicon waves.

Helicon waves are interesting because they lead, when damped, to astrong heating of the plasma, and then to high electrons densities.Plane polarized “helicon-like” waves can be excited in a plasma slab,typically in the radiofrequency (RF) range (typ. 1-100 MHz). Hence in apreferred embodiment a static magnetic field is applied in the vicinityof the antenna and the process chamber.

It has to be noticed that this is not a strict requirement for a plasmato be generated by the antenna, as the antenna can also operate withoutany (static) magnetic field, essentially by means of an inductivecoupling with the plasma.

The (static) magnetic field can be generated by different means, such aspermanent magnets as shown on FIGS. 11 and 12 of EP 2 396 804 B1, or DC(direct current) injected into the antenna on both ends of theconductive legs in each case through choke coils as shown in FIG. 18 ofEP 2 396 804 B1.

As long as the RF generator frequency corresponds to a desired resonantfrequency of the antenna, the RF energy might be injected anywhere onthe antenna structure. As a matter of fact, if the antenna is excited ata resonant frequency, the current distribution is not affected by thelocalization of the RF injection points. But the antenna impedance“seen” by the RF generator will depend on these injection points. Fromthis point of view, it is generally better, although not necessary, tofeed the antenna all across its structure, that is to say at endinjection points as shown on FIG. 13 or 14 of EP 2 396 804 B1. On FIG.13 of EP 2 396 804 B1, the RF generator feeds the antenna at twoopposing end points. On FIG. 14 of EP 2 396 804 B1, the RF generatorfeeds the antenna at two lower end injection points.

A quadratic (or bi-phased) feeding of the antenna is also possible. Anexample of such a configuration is shown on FIG. 9 of EP 2 396 804 B1.According to this embodiment the first leg and the last leg of theantenna are connected together at both ends by means of return lineseach one containing a compensation capacitor. The value of thecompensation capacitors is adjusted to compensate the inductance of thelong conductors, necessary to cover the distance between the two extremelegs. The principle of the bi-phased feeding consists in exciting theantenna with two phase shifted signals injected at two distant injectionpoints such as injection points.

FIGS. 4, 5, 6 a and 7 a show in a very schematic manner differentembodiments of the device 10.1, 10.2, 10.3, 10.4 (generally named: 10)according to the invention with a modular layout.

Basically, the layout of the device 10 is such that the device forms afirst process section where the transporting path T1 of the websubstrate is bottom up and that the device forms a second processsection where the transporting path T2 of the web substrate is top down.

The device comprises a base module 25 a with a unwind roller 20 and arewind roller 21. The base module 25 a also contains drives for drivingthe rollers 20, 21 (not shown). The base module 25 a can also contain atreatment station, e.g. a pre-treatment station as e.g. shown in theembodiment according to FIG. 12.

The device 10 further comprises at least one treatment module 25 b,25′b, 25″b which is arranged atop the base module 25 a. The at least onetreatment module 25 b, 25′b, 25″b contains a first and second treatmentstation 12 a, 12 b, each with a process chamber and a pumping system 19to evacuate the process chamber. The pumping system 19 reduces andmaintains the pressure in the region of e.g. a few Pa.

Of course, in each case a gas supply system is provided to feed theprocess chamber with a process gas. However, for reasons of simplicitythe gas supply system is not shown in FIGS. 4, 5, 6 and 7.

The treatment stations 12 a, 12 b are arranged side by side wherein theprocess direction, i.e. the transporting path T1 of the web substrate inthe first treatment station 12 a is bottom up and in the secondtreatment station 12 b top down.

Each treatment station 12 a, 12 b further comprises a feed and adischarge passage opening for the web substrate. The passage openingsform process interfaces between the modules.

On top of the modular device 10, i.e. above the at least one treatmentmodule 25 b, 25′b, 25″b, a deflection module 25 c, i.e. a top module, isarranged. The deflection module 25 c contains two deflection rollers 22a, 22 b which deflect the web substrate 15 from a bottom up direction T1into a top down direction T2.

In present case the deflection rollers 22 a, 22 b also serve as spanrollers which forms together with the span rollers 16, 17 in the basemodule 25 a a free span for the web substrate 15 in the treatmentstation 12 a, 12 b of the at least one treatment module 25 b, 25′b,25″b.

Each treatment station 12 a, 12 b of the at least one treatment module25 b, 25′b, 25″b contains at least one plasma treatment unit 13 a, 13 bwith a flat antenna as it is e.g. shown in FIGS. 1 to 3. The at leastone plasma treatment unit 13 a, 13 b can e.g. comprise a plasma sourceassembly 80 as shown in FIG. 11.

The plane antenna 9 of the at least one plasma treatment unit 13 a, 13 bis vertically (X) aligned and runs parallel to the web substrate 15.Between the web substrate 15 and the antenna of the at least one plasmatreatment unit 13 a, 13 b a vertical planer plasma zone 14 a, 14 b isformed for treating the surface of the web substrate facing the plasmazone 14 a, 14 b.

For treating the web substrate 15 the untreated web substrate 15 a iscontinuously unwound from the unwind roller 20 and deflected by thedeflection and span roller 16 into a bottom up direction. The websubstrate enters the process chamber of the first treatment station 12 aof the at least one treatment module 25 b, 25′b, 25″b through a feedpassage opening (not shown) and is transported through the firsttreatment station 12 a. Thereby the web substrate 15 is transported in abottom up direction through the plasma zone 14 a and continuouslytreated by the plasma generated by the plasma treatment unit 13 a of thefirst treatment station 12 a.

The web substrate 15 leaves the process chamber of the first treatmentstation 12 a through a discharge passage opening (not shown) and entersthe deflection module 25 c. In the deflection module 25 c the websubstrate 15 is deflected by the deflection and span rollers 22 a, 22 bfrom the bottom up direction into a top down direction T2.

The web substrate 15 during its transportation leaves the deflectionmodule 25 c and enters the process chamber of the second treatmentstation 12 b by a feed passage opening (not shown) in the top downdirection. Thereby the web substrate 15 is transported in a top downdirection through the plasma zone 14 b and continuously treated by theplasma generated by the plasma treatment unit 13 b of the secondtreatment station 12 b.

The web substrate 15 leaves the process chamber of the second treatmentstation 12 b through a discharge passage opening (not shown) in the topdown direction and enters the base module 25 a. In the base module 25 athe treated web substrate 15 b is rewound by the rewind roller 21.

The devices 10.1, 10.3, 10.4 according to FIGS. 4, 6 a and 7 a containexactly one treatment module 25 b, 25′b, 25″b which is arranged betweenthe base module 25 a and the deflection module 25 c.

The first and second station 12 a, 12 b of the treatment module 25 btogether form two plasma zones for the same treatment, e.g. coating, ofthe same surface of the web substrate 15. Due to the double treatment ofthe web surface in a first treatment station 12 a in a bottom updirection and in a second treatment station 12 b in the top downdirection the efficiency of the treatment process is increased.

The doubling of the treatment allows either the formation of thickercoatings at the same process speed or a coating of same quality atdouble speed in comparison with only one treatment step for the websurface.

In the embodiment according to FIG. 4 the process speed can be increasedup to 400 m/min instead of 200 m/min with only one treatment station 12a. The line speed of a known capacitive plasma coupled magnetron devicewith one treatment drum is for comparison 100 m/min.

The device 10.2 according to FIG. 5 contains two identical treatmentmodules 25 b as described above. The treatment modules 25 b are arrangedatop each other between the base module 25 a and the deflection module25 c.

According to this arrangement the web substrate is transported in thefirst bottom up process section through to treatment stations 12 a, 12 bof the two treatment modules 25 b and in the following second top downprocess section through another two treatment stations, 12 c, 12 d ofthe same two treatment modules 25 b. Each of the four treatment stations12 a, 12 b, 12 c, 12 d contains a plasma treatment unit 13 a, 13 b, 13c, 13 d which forms a plasma zone 14 a, 14 b, 14 c, 14 d.

Accordingly, the treatment zone quadruples. I.e., the process speed canbe increased up to 800 m/min instead of 400 m/min with only onetreatment module 25 b.

The treatment stations 12 a, 12 b of the devices according to FIGS. 6aand 7a in each case contain a first and second plasma treatment unit 13a, 13′a; 13 b, 13′b which are arranged opposite to each other so thatthe treatment path of the web substrates runs between a pair of plasmatreatment units 13 a, 13′a; 13 b, 13′b. Between the web substrate 15 andthe plasma treatment units 13 a, 13′a; 13 b, 13′b in each case a plasmazone 14 a, 14′a; 14 b, 14′b is formed, so that both sides of the websubstrate 15 are treated simultaneously.

In the device according to FIG. 6a the web substrate 30 c (see also FIG.6b ) in the first bottom up treatment station 12 a is coated on a firstweb substrate side with a first coating 30 b, e.g. a barrier coating, bya first plasma treatment unit 13 a and on a second web substrate sidewith a second coating 30 d by a second plasma treatment unit 13′a.

Subsequently the web substrate 30 in the second top down treatmentstation 12 b is coated on the first web substrate side with a thirdcoating 30 a, e.g. a second barrier coating, by a first plasma treatmentunit 13 b and on the second web substrate side again with a furthersecond coating 30 d by a second plasma treatment unit 13′b.

As the different coating layers 30 a, 30 b are only coated with oneplasma treatment unit 13 a, 13 b, the process speed is relatively lowand is about 200 m/min. However, in return the web substrate is coatedon both sides and with multi-layers within the mentioned process speed.

In the device according to FIG. 7a the web substrate 31 b (see also FIG.7b ) in the first bottom up treatment station 12 a is coated on a firstweb substrate side with a first coating 31 a, e.g. a barrier coating, bya first plasma treatment unit 13 a and on a second web substrate sidewith a second coating 31 c by a second plasma treatment unit 13′a.

Subsequently the web substrate 31 in the second top down treatmentstation 12 b is coated on the first web substrate side again with thesame first coating 31 a by a first plasma treatment unit 13 b and on thesecond web substrate side again with the same second coating 31 c by asecond plasma treatment unit 13′b.

As the coating layers 31 a, 31 c on both sides of the web substrate arein each case coated on two plasma treatment units 13 a, 13′a; 13 b, 13′bthe process speed is higher and amounts about 400 m/min.

FIG. 8 shows schematically a treatment station 40 in more detail. Thetreatment station 40 defines a process chamber 50 with a feed passageopening 48 a for the incoming web substrate 47 a and with a dischargepassage opening 48 b for the outgoing treated web substrate 47 c. Thetreatment station 40 further comprises a pumping system 42 forgenerating a low pressure in the process chamber 50.

Within the process chamber 50 a plasma treatment unit 45 with a plasmasource assembly containing a plane antenna 9 is arranged. The planeantenna 9 is connected to an RF generator 41.

The plasma treatment unit 45 also contains a bias electrode arrangementwith a bias electrode 44. The bias electrode 44 is arranged opposite tothe plasma source assembly and extends over the whole area of the planeantenna 9. The bias electrode 44 runs parallel to the plane antenna 9.The bias electrode 44 is powered by an RF generator 52. A matchingnetwork 51 is provided which interconnects the RF generator 52 and thebias electrode 44.

The bias electrode aims the control of the ion bombardment on thecoating during the coating growth process. In particular the coatingdensity, the coating chemistry (e.g. hydrogen to carbon ratio and carbonatomic orbital hybridization, sp2/sp3) and the coating amorphisation canbe controlled. As the ion bombardment is present during the full coatinggrowth time, the obtained coating is isotropic.

According to a modification of the embodiment according to FIG. 8, thebias electrode 44 a extends only over a part of the area of the planeantenna 9 as viewed in process direction. According to this modificationthe obtained coating exhibits anisotropic properties.

It is also possible to operate the treatment station 40 according toFIG. 8 without a bias electrode arrangement.

The web substrate 47 in the process chamber 50 is transported along atreatment path section between the plasma source assembly and the biaselectrode 44. The length of the treatment path section within the plasmacan e.g. be 0.2 to 1 m.

The treatment path section and accordingly the web substrate 47 b in thetreatment path section runs at a distance to the separation plane of theplasma source assembly so that the plasma zone 46 is formed between theweb substrate 47 b in the treatment path section and the separationplane. Thus, the plasma generated in the plasma zone 46 is confinedbetween the web substrate 47 b and the separation plane.

Within the process chamber 50 two deflection rollers 49 a, 49 b in thefunction of span members are provided which are spaced from each otherand which form a free span for the web substrate 47. The treatment pathsection for the web substrate 47 b lies within this free span.

Furthermore, a gas supply system 43 is provided which supplies a processgas into the plasma zone 46.

The FIGS. 9 and 10 show different layouts of the web run within theprocess chamber of a plasma treatment unit, e.g. according to FIG. 8.FIGS. 9 and 10 also show a plasma treatment unit 55, 65 with a plasmasource assembly connected to an RF generator 51, 61. Further, FIGS. 9and 10 show the incoming web substrate 57 a, 67 a and the outgoingtreated web substrate 57 c, 67 d.

In FIG. 9 the deflection rollers 59 a, 59 b, which form the spanmembers, are arranged such that the free span of the web substrate andaccordingly the treatment path section is close to the separation planeof the plasma treatment unit 55 such that the plasma zone 56 is arrangedon the side of the web substrate 57 b in the treatment path sectionfacing away from the plane antenna of the plasma treatment unit 55.

In FIG. 10 a first and second deflection roller 69 a, 69 b form a firstand second span member and are arranged such that a first free span ofthe web substrate 67 b and thus a first treatment path section areformed close to the separation plane of the plasma treatment unit 65.This, such that the plasma zone 66 is formed on the side of the websubstrate 67 b along the treatment path section facing away from theplane antenna of the plasma treatment unit 65.

The web substrate 67 is deflected on the second deflecting roller 69 bsuch that the web substrate 67 runs in opposite direction towards athird deflection roller 69 c which forms a third span member. The secondand third deflection roller 69 b, 69 c are arranged such that a secondfree span of the web substrate 67 c and thus a second treatment pathsection is formed which is spaced from the separation plane of theplasma treatment unit 65. This, such that the plasma zone 66 is arrangedbetween the first and second free span of web substrate 67 b, 67 c, i.e.between the first and second treatment path section.

The treated web substrate 57 c is deflected by a further deflectionroller 69 d before it leaves the process chamber (not shown).

The plasma source assembly according to FIG. 4, 5, 6 a, 7 a, 8, 9, 10,but also according to FIG. 12 can be designed according to FIG. 11. FIG.11 shows a plasma treatment unit with a plasma source assembly 80 and anRF generator 82. The plasma source assembly 80 comprises a plane antenna9 as e.g. shown in FIGS. 1, 2 and 3 which is connected to the RFgenerator 82.

The plane antenna 9 is embedded in a dielectric material 83. The plasmasource assembly 80 further comprises a conductive bottom plate 85, e.g.of metal, which defines a lower termination of the plasma sourceassembly 80. The plasma source assembly 80 further contains a dielectrictop plate 84, e.g. made of glass or ceramics, which defines an uppertermination of the plasma source assembly 80. The dielectric top plate84 is facing the plasma zone of the plasma treatment unit and forms theseparation plane.

The dielectric material 83 is confined between the conductive bottomplate 85 and the dielectric top plate 84. The dielectric material 83 isfurther confined by a lateral frame 86 which laterally encloses theplasma source assembly 80.

The ladder-type, plane antenna 9 contains a plurality of parallel legs1, 2 which are connected with shorter elements each containing acapacitor 5. The transporting direction P′ of the web substrate can beparallel to the legs 1, 2. However, more uniform treatment results areachieved, when the transporting direction P of the web substrate runsperpendicular to the legs 1, 2.

FIG. 12 shows a cross-section of a schematically outlined device 90according to a further embodiment. The device comprises a base module 95a with an unwind roller 91 to unwind the untreated web substrate 94 aand a rewind roller 93 to rewind the treated web substrate 94 b.

The base module 95 a further comprises a pre-treatment station 92 a witha plasma treatment unit according to the invention which is arranged ina rear section of the base module 95 a. Span rollers 98 a, 98 b define afree span which contains the treatment path section of the web substrate94 in the treatment station 92 a. The free span and accordingly thepre-treatment path section for the web substrate 94 and the planeantenna are vertically (X) aligned.

In the pre-treatment station 92 a the web substrate 94 is prepared for asubsequent coating. A task of the preparation process is to increase theadhesion of the coating on the web substrate 94.

Furthermore, a treatment module 95 b is arranged atop the base module 95a. The treatment module 95 b contains two treatment stations 92 b, 92 c,each with a plasma treatment unit according to the invention for coatingthe web substrate 94. The treatment stations 92 b, 92 c are arrangedside by side. The first treatment station 92 b is arranged in a backsection of the treatment module 95 b and operated in a bottom up processdirection P. The second treatment station 92 c is arranged in a frontsection of the treatment module 95 b and is operated in a top downprocess direction P.

Span rollers 98 a, 98 b in each case define a free span which containsthe treatment path section of the web substrate 94 in the treatmentstations 92 b, 92 c. The free spans and accordingly the treatment pathsections for the web substrate 94 and the plane antenna are vertically(X) aligned.

On top of the device 90 and atop the treatment module 95 b a top module95 c is arranged with driven deflection rollers 97 a, 97 b which deflectthe web substrate 94 from a bottom up process direction into a top downprocess direction. The deflection rollers 97 a, 97 b also serve ascooling rollers.

The device 90 is operated by continuously unwinding an untreated websubstrate 94 a from the unwind roller 91 and continuously rewinding thetreated web substrate 94 b on the rewinding roller 93. During thisprocess the web substrate 94 is transported in a back section of thedevice 90 via deflection rollers in a bottom up process directionthrough the pre-treatment station 92 a. The web substrate 94 ispre-treated while passing through the pre-treatment station 92 a.

Subsequently, the pre-treated web substrate 94 leaves the base module 95a and enters the treatment module 95 b in the back section of the device90, still in a bottom up process direction P.

The web substrate 94 is transported in the back section of the device 90in a bottom up process direction through the first treatment station 92b of the treatment module 95 b. The web substrate 94 is coated whilepassing through the first treatment station 92 b.

Subsequently, the coated web substrate 94 leaves the treatment module 95b and enters the top module 95 c. In the top module 95 c the websubstrate 94 is deflected from the bottom up process direction P intothe top down process direction via deflecting rollers 97 a, 97 b.

Subsequently, the coated web substrate 94 leaves the top module 95 c andenters again the treatment module 95 b, this time in the top downprocess direction P and in a front section of the treatment module 95 bor the device 90 respectively.

The web substrate 94 is transported in the front section of the device90 in the top down process direction through the second treatmentstation 92 c of the treatment module 95 b. The web substrate 94 iscoated while passing through the second treatment station 92 c.

Subsequently, the treated web substrate 94 b leaves again the treatmentmodule 95 b in the top down process direction and enters the base module95 a again.

In the base module 95 a a quality control system 100 is arranged alongthe transporting path of the treated web substrate 94 b. The qualitycontrol system 100 can comprise sensors which work on the principle ofcoating optical density measurement.

After the passing the quality control system 100 the treated websubstrate 94 b is further transported via deflection rollers to therewind roller 93 and rewound. A lay on roller 99 with constant distanceassures a wrinkle free winding.

To ensure the required tension of the web substrate 94 along its processpath, dancer rollers 96 can be provided.

FIG. 13 shows an alternative design of a plasma treatment station 70 awith a rotatable drum 72 and with a curved plasma source assembly 74 ahaving a curved extensive antenna 73 a. The curved shape of theextensive antenna 73 a is adapted to the shape of the curved surfacearea of the rotatable drum 72. Accordingly, the cover plate of theplasma source assembly 74 a facing the web substrate 71 is curved aswell. The surface of the cover plate forms the separation surface.

The plasma source assembly 74 a with its curved, extensive antenna 73 ais arranged at a distance to the rotatable drum 72 so that a curved gap75 a is formed between the rotatable drum 72 and the plasma sourceassembly 74 a. The plasma zone is formed in the space formed by thecurved gap 75 a.

FIG. 14 shows a further alternative design of a plasma treatment station70 b with a rotatable drum 72 and with two plane plasma source assembly74 b having a plane antenna 73 b. The cover plate facing the rotatabledrum 72 towards the transporting path of the web substrate 71 is plane.The surface of the cover plate forms the separation surface.

The plasma source assembly 74 b with its plane antenna 73 b is arrangedat a distance to the rotatable drum 72 so that a gap 75 b is formedbetween the rotatable drum 72 and the plasma source assembly 74 b. Theplasma zone is formed in the space formed by the gap 75 b.

In operation, the web substrate 71 according to FIGS. 13 and 14, in theregion of the formed plasma zone, rests on a curved circumferentialtreatment surface area of the drum 72 and is transported at the rotationspeed of the rotating drum 72, while being coated.

FIG. 15 shows a further layout of a plasma treatment station with aplasma treatment unit 115 and the web run within plasma treatmentstation.

The plasma treatment unit 115 contains a plasma source assembly with aplane antenna embedded in a dielectric material. The plasma sourceassembly is connected to an RF generator 112.

The plasma source assembly comprise on both opposites sides a dielectriccover plate which, in each case, forms a separation surface towards aweb substrate treatment path. I.e. instead of a conductive base plate asecond dielectric cover plate is provided.

As a consequence on both sides of the cover plate a plasma zone 116 a,116 b is formed. The web substrate 117 now runs along a first treatmentpath parallel to the plane antenna at a distance to the first coverplate so that a first plasma zone 116 a is formed between the websubstrate 117, i.e. the first treatment path, and the first cover plate.

Subsequent to the first treatment path the web substrate 117 isdeflected via a deflection roller 118 in an opposite transport directionat a distance and parallel to the first treatment path. The deflectedweb substrate 117 passes now the plane antenna, i.e. the plasma sourceassembly, on the opposite side and at distance to the second cover platealong a second treatment path. Between the web substrate 117, i.e. thesecond treatment path, and the second cover plate a second plasma zone116 b is formed. In the second plasma zone 116 b a second treatment stepis carried out on the surface of the web substrate 117 already treatedin the first plasma zone 116 a. The web substrates may be cooled oradjusted to a desired web temperature by the e.g. deflection roller 118being designed as a cooling roller. However, providing a separatecooling roller is also possible.

Furthermore, a gas supply system, in particular gas injectors 114, isprovided which supplies a process gas into the plasma zones 116 a, 116b.

Accordingly, the plane antenna, i.e. the plasma source assembly, isarranged between a first and second parallel web substrate treatmentpath.

FIG. 16 shows a further layout of a plasma treatment station with aplasma treatment unit 115 and the web run within plasma treatmentstation. The plasma treatment station is similar to the embodimentaccording to FIG. 15.

However, in this embodiment, two different substrate webs are treatedalong the first and second parallel web substrate treatment paths, inthe plasma zones 116 a and 116 b, with the same plasma treatment unit115 containing the same plasma source assembly arranged in between thetwo treatment paths as disclosed in FIG. 15. Thus, a first web substrate119 a is forwarded from a first unwinding storage reel 120 a or priortreatment step, passing along the first treatment path, by the plasmasource, and after plasma treatment forwarded to a next step or wound uponto a subsequent, first winding storage reel 120 b, whilesimultaneously, a second web substrate 119 b is forwarded from a secondunwinding storage reel 121 a or treatment step, passing along the secondtreatment path, by and on the other side of the plasma source, and afterplasma treatment forwarded to a next step or wound up onto a second,subsequent, winding storage reel 121 b.

The web substrates may be cooled or adjusted to a desired webtemperature by cooling rollers at the inlets and outlets of the plasmatreatment paths.

Furthermore, a gas supply system, in particular gas injectors 114, isprovided which supplies a process gas into the plasma zones 116 a, 116b.

1. A device for continuously treating a web substrate in a plasmaenhanced process, the device comprising: at least one treatment stationincluding a process chamber, wherein at least one plasma treatment unitis allocated to the at least one treatment station which is designed toform a plasma zone within the process chamber for treating a surface ofthe web substrate a transporting system configured to continuouslytransport the web substrate through the at least one treatment station,with an unwind roller and a rewind roller, wherein the transportingsystem defines a transporting path of the web substrate through theprocess chamber, wherein the at least one plasma treatment unitcomprises at least one extensive antenna and at least one radiofrequencygenerator configured to excite said at least one extensive antenna to atleast one of its resonant frequencies, wherein the at least oneextensive antenna comprises a plurality of interconnected elementaryresonant meshes, each of the resonant meshes comprising at least twoconductive legs and at least two capacitors, and wherein thetransporting system in the process chamber defines a treatment pathsection for the web substrate, wherein the treatment path section forthe web substrate lies opposite to the extensive antenna.
 2. The deviceaccording to claim 1, wherein the extensive antenna comprises one of: aplane antenna; or a curved antenna.
 3. The device according to claim 1,wherein the plasma treatment unit contains a separation surface whichphysically separates the extensive antenna from the plasma zone.
 4. Thedevice according to claim 3, wherein the plane antenna and the treatmentpath section are vertically aligned.
 5. The device according to claim 3,wherein the transporting system contains a first and second span memberwhich are spaced from each other, wherein between the span members, afree span for the web substrate is defined which contains the treatmentpath section for the web substrate.
 6. The device according to claim 3,wherein the treatment path section of the web substrate runs at adistance from the separation surface so that the plasma zone is formedbetween the treatment path section of the web substrate and theseparation surface.
 7. The device according to claim 3, wherein thetreatment path section of the web substrate runs close to the separationsurface so that the plasma zone is formed on the side of the websubstrate which is facing away from the extensive antenna.
 8. The deviceaccording to claim 3, wherein the treatment path section of the websubstrate forms the separation surface so that the plasma zone is formedon the side of the web substrate which is facing away from the extensiveantenna.
 9. The device according to claim 1, wherein the treatmentstation contains a feed passage opening configured to feed the websubstrate into the process chamber and a discharge passage openingconfigured to discharge the treated web substrate from the processchamber.
 10. The device according to claim 1, wherein the treatmentstation contains a gas supply system configured to supply a process gasto the plasma zone in the process chamber.
 11. The device according toclaim 1, wherein the treatment station contains a pumping systemconfigured to remove gaseous components from the process chamber. 12.The device according to claim 1, wherein within a common process chamberat least two plasma treatment units or extensive antennas respectivelyare arranged, in each case forming a plasma zone for a surface treatmentof the web substrate.
 13. The device according to claim 1, wherein theat least one treatment stations comprises a first treatment station withat least one plasma treatment unit, and arranged in processing directionsubsequent to the first treatment station, a second treatment stationwith at least one plasma treatment unit, wherein the transporting systemis designed such that the web substrate first can be transported throughthe first treatment station and subsequently through the secondtreatment station in a continuous manner.
 14. The device according toclaim 13, wherein in processing direction between the plasma treatmentunit of a preceding treatment station and the plasma treatment unit of asubsequent treatment station at least one deflection member is arranged,which deflects the web substrate such, that the transporting directionof the web substrate through the plasma zone of the plasma treatmentunit of the subsequent treatment station is opposite or at an angle tothe transporting direction of the web substrate through the plasma zoneof the plasma treatment unit of the preceding treatment station.
 15. Thedevice according to claim 7, wherein a first treatment path section ofthe web substrate runs close to the separation surface or forms theseparation surface and a second treatment path section runs at adistance to the separation surface and the first treatment path section,so that the plasma zone is formed between the first and second treatmentpath section of the web substrate.
 16. The device according to claim 1,wherein the device has a modular layout and contains a base module withan unwind roller and a rewind roller and a treatment module with atleast a treatment station.
 17. The device according to claim 1, whereinthe device contains at least two process sections, wherein to eachprocess section at least one plasma treatment unit for treating the websubstrate is allocated, and wherein the process direction in one processsection is bottom up and wherein the process direction in the otherprocess section is top down.
 18. The device according to claim 1,wherein the transporting system contains a rotatable drum, wherein thetreatment path section of the web substrate is curved and runs along aperipheral surface section of the rotatable drum which defines a curvedresting surface for the web substrate in the process chamber.
 19. Thedevice according to claim 1, wherein the treatment unit is designed toestablish a plasma zone on both sides of the antenna, lying opposite toeach other.
 20. A method for continuously treating a web substrate in aplasma enhanced process with a device according to claim 1, the methodcomprising: providing a web substrate with a first web end section whichis placed on an unwind roller and with a second web end section which isplaced on a rewind roller and with an intermediate web section;generating a plasma in the plasma zone of the at least one plasmatreatment unit; unwinding the web substrate from the unwind roller andrewinding the treated web substrate by the rewind roller, therebytransporting an intermediate web section of the web substrate along thetreatment path section in the at least one treatment station through theplasma zone of the plasma treatment unit and thereby plasma treating asurface of the web substrate.